How are panoramas created?
A series of photographs are needed for a panorama. The camera stays at the same place and is rotated or tilted.
Generally, panoramas can be photographed with any camera, from the cheapest «Click-o-Matic» to the Spheron SpheroCamHDR, depending on the budget. Cylindrical panoramas can be shot with the handheld camera, the result may be such that there is something left to be desired — but it is doable. A digital camera is an advantage but not mandatory.
A cylindrical panorama made from six photographs glued together, the seventh photograph is a copy of the first one. Another example made from 11 photographs, the 12th again a copy of the first (both panoamas from the early seventies: Dartmoor, England and Font Romeau, Pyrenees, France).
There is a difficulty to correct photographic prints and the lower example shows what happens if the camera is not correctly aligned horizontally. To align the camera horizontal, a water level is almost mandatory. There are some very handy levels that can be put on the holder for the flashlight.
When purchasing a level, check that it can be fixed also turned by 90° to assure the levels also work if the camera is set for a portrait shot. Even though panoramas can be made with the handheld camera, the use of a stable tripot is highly recommended.
In order to get more height from the scenery , move the camera in portrait position. More pictures will be needed to get a full circle, of course.
When the camera is rotated or tilted for the next exposure, keep in mind that at least 10% of the scenery from the previous picture is shown in the new one. If a wide angle lens is used, more overlap is necessary because such a lens distorts considerably towards the edges. These distortions must be calculated and compensated for by the «Stitcher» in order to assemble the pictures seamless to a panorama. For a cylindrical 360° panorama, you soon end up with a dozen or more photographs.
Parallax-Errors
Horizontal and vertical cylindrical panoramas can be made with the handheld camera, better use
a tripod, though. What has been just said applies for wide landscapes. It does not apply to
panoramas made in a room or with objects close to the camera. A perfect panorama in a room
necessitates that the camera is rotated and tilted at the exact focal point. This is not the
case for a handheld camera — not even if one turns around on the own axes — and neither
on the tripod. The solution is a panorama-head on the tripod. Panorama-heads can be purchased for
a relatively high price, but can be home made with some mechanical aptitude. Different examples
of successful tinkering can be found on the Internet. I do not (yet) use a panorama-head.
Fisheye
Fisheye lenses can be used for horizontal cylindrical 360 ° panoramas and skydome panoramas.
The field of view of the lens is only 180° but if it is tilted up vertically to the zenith,
a 360° panorama appears along the horizon. If such a skydome panorama is transformed into
the spherical projection, the sky can be cut away and what remains is a cylindrical panorama.
Fisheye lenses are rather expensiv, but this is only a part of the problem. Far worse is the fact that they do not portray the full 180° on a DSLR camera — but do on a SLR camera. This does not matter that much if the camera is held horizontally to get a very wide angle photograph. It is only 120°, oh, well. If the camera is pointed to the sky, however, the image stops well before the horizon.
SLR cameras use film with a picture size of 36 mm by 24 mm. The lenses are made for that size. The CMOS or CCD chip of a DSLR camera is usually smaller, perhaps 24 mm by 16 mm. In this case, a 200 mm telelens becomes a more powerful 300 mm zoom lens but at the same time, a 18 mm wideangle lens is reduced to a narrower 27 mm lens. In this example, the field of view is reduced by a third and a 180° fisheye describes only 120°. When purchasing a DSLR camera, it is more important to mind that the size of the chip is 36 mm by 24 mm than trying to get the most megapixels.
Spherical Panoramas
It is almost impossible to do spherical panoramas without a panorama-head and a tripod. Generally,
you go about it the same way as for a horizontal cylindrical panorama. After each full turn, the camera
is tilted upwards and another full circle is photographed, then again tilted upwards and so on until
there is only one single zenith photograph left. This is repeated downwards. The last picture
for the nadir is done with the camera handheld after the tripod has been put out of the way. To get
the nadir right in the final panorama, a bit of cheating cannot be prevented. Depending on the lens
used, 40 to 60 photographs are needed to get a complete panorama.
Of course, you could always use a mirrror ball, as shown under the HDRI topic. But the quality is so very much lower.